Eric do you have any references to support this idea?Eric Janson wrote: ↑Thu Jun 14, 2018 8:28 pm Lower visibility results in the horizon being closer which makes the horizon line lower when looking outside. This creates the illusion of the aircraft pitch being high with an instinctive nose down input being the result. In this incident this is exactly what happened but the report doesn't discuss optical illusions.
WestJet almost puts one in the drink
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Re: WestJet almost puts one in the drink
Re: WestJet almost puts one in the drink
You can easily check that yourself. For clarity, the horizon is defined as the apparent line that separates earth from sky (clouds).Cliff Jumper wrote: ↑Sat Jun 16, 2018 6:56 pmEric do you have any references to support this idea?Eric Janson wrote: ↑Thu Jun 14, 2018 8:28 pm Lower visibility results in the horizon being closer which makes the horizon line lower when looking outside. This creates the illusion of the aircraft pitch being high with an instinctive nose down input being the result. In this incident this is exactly what happened but the report doesn't discuss optical illusions.
If you are lined up on the runway, imagine the visibility is good and you can see all runway edge lights ahead of you. The horizon is above the edge of he runway. Now the visibility goes down, and you can only see half the runway edge lights. The horizon would now be at the points where you see those last runway edge lights. Now repeat this thought experiment and imagine the visibility goes down and you can only see 10 runway edge lights. Then 9, 8... etc. The horizon would always move down. If you were to draw a line on the windshield for every option during this experiment, you'd see the line move down.
Next, imagine you are in the airplane, 200 ft above the runway elevation, instead of on it. You could do the same experiment.
Now, imagine you are flying and you are used to having -depending on plane etc- a +2 degree attitude during final approach. You have that in your attitude indicator and you are nice and stable. You are now visual at minima and in your enthousiasm you ignore your attitude indicator for a moment and instinctively try to put your nose to a 2 degree attitude, looking outside at the horizon. We have established that lower visibility will give a lower horizon. You are now using a lower reference point to set your +2 degree, and will this have a lower attitude than you desire.
As an AvCanada discussion grows longer:
-the probability of 'entitlement' being mentioned, approaches 1
-one will be accused of using bad airmanship
-the probability of 'entitlement' being mentioned, approaches 1
-one will be accused of using bad airmanship
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Re: WestJet almost puts one in the drink
So, you're suggesting that this is soooo obvious that it is common sense and doesn't need to be written down anywhere?
There are quite a few (thousand) books on flight crew illusions, I just can't remember this in any of them. But, I fully admit, I might have missed it.
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Re: WestJet almost puts one in the drink
Cliff Jumper wrote: ↑Sun Jun 17, 2018 7:56 amSo, you're suggesting that this is soooo obvious that it is common sense and doesn't need to be written down anywhere?
There are quite a few (thousand) books that describe flight crew illusions, I just can't remember this in any of them. But, I fully admit, I might have missed it.
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Re: WestJet almost puts one in the drink
So, you're suggesting that this is soooo obvious that it is common sense and doesn't need to be written down anywhere?
There are quite a few (thousand) books that describe flight crew illusions, I just can't remember this in any of them. But, I fully admit, I might have missed it.
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Re: WestJet almost puts one in the drink
I wrote out the whole procedure how you can check it out yourself. Any pilot should be able to follow it. So yes, easy to verify if it is accurate.Cliff Jumper wrote: ↑Sun Jun 17, 2018 7:56 amSo, you're suggesting that this is soooo obvious that it is common sense and doesn't need to be written down anywhere?
There are quite a few (thousand) books on flight crew illusions, I just can't remember this in any of them. But, I fully admit, I might have missed it.
I never said it was obvious. It is one of those things that usually don't matter.
If you disagree, let me know at which step it fails or where the error is.
As an AvCanada discussion grows longer:
-the probability of 'entitlement' being mentioned, approaches 1
-one will be accused of using bad airmanship
-the probability of 'entitlement' being mentioned, approaches 1
-one will be accused of using bad airmanship
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Re: WestJet almost puts one in the drink
@digits_
Semantics maybe - but in reduced visibility you have marginal to no depth perception. You cannot accurately determine height and distance. This is why PAPI/Approach Lights/DME was invented.
@Cliff Jumper
Optical illusions discussed here - shortened horizon distance is mentioned.
https://www.skybrary.aero/bookshelf/books/812.pdf
The ALAR toolkit is worth downloading as it has a great deal of useful information
Semantics maybe - but in reduced visibility you have marginal to no depth perception. You cannot accurately determine height and distance. This is why PAPI/Approach Lights/DME was invented.
@Cliff Jumper
Optical illusions discussed here - shortened horizon distance is mentioned.
https://www.skybrary.aero/bookshelf/books/812.pdf
The ALAR toolkit is worth downloading as it has a great deal of useful information
Always fly a stable approach - it's the only stability you'll find in this business
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Re: WestJet almost puts one in the drink
Bit Eric, that reference gives the exact opposite of what you are saying. It says that in haze, you could interpret being too low, and pull up.
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Re: WestJet almost puts one in the drink
Page 4 - Flight Path Monitoring.
Always fly a stable approach - it's the only stability you'll find in this business
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Re: WestJet almost puts one in the drink
Still can't find the part where it says 'reduced visibility causes the illusion of increased pitch'.
But, granted, I don't read good.
But, granted, I don't read good.
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Re: WestJet almost puts one in the drink
Final report released.
http://www.bst-tsb.gc.ca/eng/rapports-r ... 7f0052.pdf
Lowest recorded altitude 39 feet!
Someone should send Lauren Stewart a copy of the report.
http://www.bst-tsb.gc.ca/eng/rapports-r ... 7f0052.pdf
Lowest recorded altitude 39 feet!
Someone should send Lauren Stewart a copy of the report.
Always fly a stable approach - it's the only stability you'll find in this business
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Re: WestJet almost puts one in the drink
39 feet from what point on the aircraft?
Re: WestJet almost puts one in the drink
Wherever the source for the egpws comes from. I would guess a rad alt on the bottom of the fuselage.
That was an overly detailed report, they really pushed the paper well. No FDR data to go on either.
Re: WestJet almost puts one in the drink
That is the report that was released on June 4 2018 and Donald posted it that day. Eric we already hashed it out!Eric Janson wrote: ↑Fri Aug 24, 2018 12:13 pm Final report released.
http://www.bst-tsb.gc.ca/eng/rapports-r ... 7f0052.pdf
Lowest recorded altitude 39 feet!
Someone should send Lauren Stewart a copy of the report.
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Re: WestJet almost puts one in the drink
Ok thanks - I missed that.J31 wrote: ↑Fri Aug 24, 2018 3:04 pmThat is the report that was released on June 4 2018 and Donald posted it that day. Eric we already hashed it out!Eric Janson wrote: ↑Fri Aug 24, 2018 12:13 pm Final report released.
http://www.bst-tsb.gc.ca/eng/rapports-r ... 7f0052.pdf
Lowest recorded altitude 39 feet!
Someone should send Lauren Stewart a copy of the report.
Always fly a stable approach - it's the only stability you'll find in this business
Re: WestJet almost puts one in the drink
At night
Still on the vertical profile
On an offset lateral profile where lights were misleading
Nobody got a picture of that
Re: WestJet almost puts one in the drink
I can understand that part of the problem the crew had in SFO because there are not many runways with airplanes on it pointed towards you with all those bright lights blinding you.On an offset lateral profile where lights were misleading
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Re: WestJet almost puts one in the drink
That brings up an interesting topic; the use of the taxi-light while holding short?
I always have it on anytime I’m away from the apron, provided it isn’t pointed directly AT another aircraft. Even when not in motion, I’ll generally leave it on unless giving way to another aircraft.
They’re usually aimed low enough that it won’t “blind” anyone else. What’s everyone else’s opinion on this? Looks like in the AC incident it helped a bit.
I always have it on anytime I’m away from the apron, provided it isn’t pointed directly AT another aircraft. Even when not in motion, I’ll generally leave it on unless giving way to another aircraft.
They’re usually aimed low enough that it won’t “blind” anyone else. What’s everyone else’s opinion on this? Looks like in the AC incident it helped a bit.
Re: WestJet almost puts one in the drink
A lot of airline SOP's have the taxi light on when ever moving under power day and night.